Suppression of the Coffee-Ring Effect and Evaporation-Driven Disorder to Order Transition in Colloidal Droplets

Das, Shyamashis and Dey, Atreya and Reddy, Govardhan and Sarma, D D (2017) Suppression of the Coffee-Ring Effect and Evaporation-Driven Disorder to Order Transition in Colloidal Droplets. In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 8 (19). pp. 4704-4709.

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Abstract

The formation of a ring-like deposit at the periphery of a drying colloidal droplet is a vexing problem in many applications. We show a complete suppression of such deposits when a droplet of aqueous colloidal suspension, deposited on a glass substrate coated with a thin layer of silicone oil, is evaporated. This coating prevents the periphery of the aqueous droplet from getting pinned to the substrate and helps in suppressing the ring formation. It also decreases the surface area of the droplet, thereby decreasing the evaporation rate. These two factors together, driving the colloidal particles slowly to the center of the droplet, contribute to form an ordered crystallite at the end of the evaporation process. Brownian dynamics simulations performed to study ordering in the aggregate show that the spherical colloidal particles form face-centered cubic structures. Experiments and simulations show that slow rates of droplet evaporation and smaller-sized colloidal particles further lead to high-quality ordered colloidal crystallites.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY LETTERS
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	03 Nov 2017 10:46
Last Modified:	03 Nov 2017 10:46
URI:	http://eprints.iisc.ac.in/id/eprint/58158

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